Truck mixers for the delivery of the mixed ingredients of concrete must be washed out at the end of a work period or day and before the usual remaining concrete hardens and is then extremely difficult to remove. The separation of the sand and gravel from the washout water for their reusing is readily provided for with a settling tank. However, the cement does not settle as readily and the recovered cement is not reusable.
A typical prior art washout reclamation system includes a long tank from which some number such as four to eight truck mixers may draw the required washout water and into which the washout is directed for the subsequent separation of the several materials. Scrapers operated by parallel chains push the settled material up the inclined end of the tank for removal and normally operate continuously at a very low speed to prevent the curing cement from "freezing up" the chains.
As soon as and while washout water is being withdrawn from the tank, the chains operate at a relatively high speed to remove the aggregate and sand which settle immediately. A deflector directs these materials onto a belt conveyor which carries them to a storage location. Such separation and removal of the aggregate and sand is completed in only a few minutes after the last of a series of truck mixers have been washed out. The chain and scrapers then resume their continuous slow speed operation and the mentioned deflector is moved so that the continuing discharge of the cement slurry or grout will fall directly into a storage pit directly below the discharge end of the tank. The cement settles and the grout is discharged from the tank only very slowly and similarly accumulates slowly in the pit where it may harden. When the accumulation warrants, a front end loader is driven into the pit and the grout or the hardened cement is broken up and removed for disposal generally as land-fill.
A relatively large pit is necessary to receive the grout and must extend below the belt conveyor. The required below-grade elevation of the floor of the pit requires guard rails and other provisions such as drainage.
The present invention derives from attempts to extend the deflector so that no part of the conveyor need be over the pit with the thought that the deflector then could be moved somehow whenever the accumulated grout is to be removed such that a relatively shallow pit would then be permitted.
Such attempts have not been practicably successful. The main difficulty, of course, is that the deflector as a gravity conveyor requires a considerable downward incline.
The present invention has as its main object to allow a shallow pit for the spent cement or grout to extend below the belt conveyor and requires no deflector.